cpu scheduling
DESCRIPTION
CPU scheduling. Introduction to Operating Systems: Supplemental Module. The processes. Arrival time. CPU burst. 0 13 16 20. P1: 4 36 8 112 1. I/O burst. P2: 23 40 2. P3: 4 20 112 40 2 40 2 40 1. P4: 2 150 3 10 1. Gantt chart. 0. FCFS. 0 13 16 20. - PowerPoint PPT PresentationTRANSCRIPT
CPU scheduling
Introduction to Operating Systems: Supplemental Module
The processes
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0
0
13
16
20
Arrival time
CPU burst
I/O burst
Gantt chart
FCFS
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4
0 4 13 36 40 42
0
13
16
20
Gantt chart
Which process goes next?
FCFS
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4
0 4 13 36 40 42
0
13
16
20
Gantt chart
Which process goes next?
40
76
60
192
Time next ready
FCFS
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4 P1 idle P3
0 4 13 36 40 42 50 60 172
0
13
16
20
Gantt chart
40
76
60
192
Time next ready
FCFS
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4 P1 idle P3 P2 P1 idle P4 0 4 13 36 40 42 50 60 172 174 175 192
0
13
16
20
Gantt chart
162
76
212
192
SRTF
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4 P2
0 4 13 16 20 22
0
13
16
20
Gantt chart
Which process goes next, and when?
SRTF
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0
13
16
20
40
Run
40
172
Time next ready
P1 idle P2 P3 P4 P2
0 4 13 16 20 22
Gantt chart
SRTF
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0
13
16
20
162
End
Run
172
P1 idle P2 P3 P4 P2 P1 P3 P2 P3
0 4 13 16 20 22 42 50 82 84
Gantt chart
Which process goes next, and when?
SRTF
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0
13
16
20
End
End
205
185
P1 idle P2 P3 P4 P2 P1 P3 P2 P3 P1 P3 idle P4 0 4 13 16 20 22 42 50 82 84 162 163 165 172 175
Gantt chart
RR, Q = 10
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4
0 4 13 23 27 29
0
13
16
20
Gantt chart
Which process goes next, and when?
RR, Q = 10
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4 P2
0 4 13 23 27 29 42
0
13
16
20
Gantt chart
40
82
47
179
RR, Q = 10
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4 P2 P1 P3 P2 P3
0 4 13 23 27 29 42 50 90 92
0
13
16
20
Gantt chart
162
End
Run
179
RR, Q = 10
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
P1 idle P2 P3 P4 P2 P1 P3 P2 P3 P1 P3 idle
0 4 13 23 27 29 42 50 90 92 162 163 165
0
13
16
20
Gantt chart
End
End
205
179
HRRN
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
1 idle 2
0 4 13 36
0
13
16
20
Gantt chart
40
76RR4 = 1+ (36-20)/2 = 9
RR3 = 1+ (36-16)/4 = 6
HRRN
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
1 idle 2 4 3
0 4 13 36 38 42
0
13
16
20
Gantt chart
40
76
62
188
HRRN
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
1 idle 2 4 3 1 idle 3
0 4 13 36 38 42 50 62 174
0
13
16
20
Gantt chart
162
76
214
188
RR2 = 1+ (174-76)/2 = 50
RR1 = 1+ (174-162)/1 = 13
HRRN
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
1 idle 2 4 3 1 idle 3 2 1 idle 4 idle 4
0 4 13 36 38 42 50 62 174 176 177 188 191 201
0
13
16
20
Gantt chart
end
end
214
end
MLFQ: Q0 = 8, Q1 = 16, Q2 =
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0 4 13 21 25 27
0
13
16
20
Gantt chart
40
q1
45
177
1 idle 2 3 4 2
15
MLFQ: Q0 = 8, Q1 = 16, Q2 =
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0 4 13 21 25 27 40 48 56
0
13
16
20
Gantt chart
160
q1
q1
177
1 idle 2 3 4 2 1 3
2
104
MLFQ: Q0 = 8, Q1 = 16, Q2 =
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0 4 13 21 25 27 40 48 56 58 98
0
13
16
20
Gantt chart
160
98
q2
177
1 idle 2 3 4 2 1 3 2 3
64
MLFQ: Q0 = 8, Q1 = 16, Q2 =
P1: 4 36 8 112 1
P2: 23 40 2
P3: 4 20 112 40 2 40 2 40 1
P4: 2 150 3 10 1
0 4 13 21 25 27 40 48 56 58 98 100 160 161 165
0
13
16
20
Gantt chart
end
end
q2
190
1 idle 2 3 4 2 1 3 2 3 2 3 1 3 idle
4